The metal/semiconductor Schottky junction of a III-V Schottky diode has the characteristics of a monocarrier and a fast switching speed, and can be used in the fields of photoelectric and microwave applications. However, the surface conditions of the III-V Schottky diode, such as the impurity content and surface free radicals, will influence its barrier hight. The energy barrier of a Schottky diode is called the Schottky barrier. If the surface defects of the diode can be minimized, the Schottky barrier height will be increased and the diode will be more useful. Please refer to FIG. 1 showing a conventional structure of a Schottky diode. The diode includes a metal layer 1, a Schottky barrier layer 2, and a substrate 3. The metal layer 1 is usually made of a noble metal for conducting the electricity. The Schottky barrier layer 2 is a thin aluminum layer sputtered on the substrate 3. Conventionally, it has been found that the Schottky barrier height can effectively increase after treating the substrate with a solution containing sulfur ions. However, the sulfur ion in the surface of the substrate will evanesce off after using it for a period of time or after working under a high temperature. Then, the Schottky barrier height will be lowered again. Another method disclosed that the Schottky barrier can also be increased after treating the substrate with aluminum fluoride solution (AlF.sub.3), but the ideality factor of this method is too high to be applied in the industry. (see J. Applied Physics, Vol. 78, p. 291 (1995))
Accordingly, the present invention provides an easy and economical method for producing a III-V Schottky diode and provides a new diode structure. This method quite useful for every kind of III-V semiconductor structure.